Determine the role of guanylate cyclase in the mature villus cell particularly in relationship to its microvillus subcellular location which raises questions as to the role of this enzyme and cGMP in secretion and absorption. Further characterization of the glycoproteins of the lateral-basal membrane, comparing them with Golgi and microvillus membrane and determining their role and the role of sialyltransferase of the lateral-basal membrane in cellular adhesion. Isolation of the crypt cell surface membrane. Different techniques involving fixation of the surface membrane are being tested in order to have the ability to physically separate the surface membrane from internal membranes. If this is achieved work can proceed on characterizing the crypt surface membrane. Con A agglutination and terminal mannose residues of cell surface membrane receptors. We are chemically synthesizing Sepharose beads with different sugars covalently linked to the Sepharose and with varying lengths of linkage arm. This should enable us to test as determinants in Con A agglutination of cells (1) the specificity of the sugar requirement, and (2) the length of the oligosaccharide extending out from cell surface. Cancer-associated isoenzyme of serum galactosyltransferase. We are continuing to evaluate this isoenzyme clinically and to examine its biological significance. Obtaining large amounts of this isoenzyme is important in achieving purification and characterization of the isoenzyme. We are analyzing malignant effusions as a source for this isoenzyme. BIBLIOGRAPHIC REFERENCES: Podolsky, D.K. and Weiser, M.M. Role of cell membrane galactosyltransferase in concanavalin A agglutination of erythrocytes. Biochem. J. 146:213-221, 1975. Weiser, M.M., LaMont, J.T. and Walker, W.A. Alpha-1-Antitrypsin deficiency - a defect of secretion. New Engl. J. Med. (Editorial) 292:205-206, 1975.